1. Field of the Invention
The present invention relates to an image processing method.
2. Description of the Related Art
In recent years, as digital still cameras or the like have been widely used, personal users who handle digitized images and pictures have been increasing. Many of the images and pictures have been increasingly disclosed to the public through the Internet or intranets. In some cases, specific image data is distributed at charge to a person who wishes to buy the data, or to a specific user through a network site, which can be accessed by unspecified users. In such cases, generally, a password is set to obtain the image, or the image to be distributed is scrambled or mosaicked. To distribute a scrambled image, a transmitter side must have scrambling means, and a receiver side must have scramble releasing (descrambling) means. A scanning line signal switching method or a scanning line shifting method, utilizing random arrangement, are known as the image scrambling methods. In the former method, the order of data in a scanning line is changed. In the latter method, data is shifted from one scanning line to another. Further, Jpn. Pat. Appln. KOKAI Publication No. 5-103326 discloses a method for produce a scrambled image by forming new two field images from two field images in one frame so as not to reduce the compression ratio.
In the case where the password setting method is employed, it is necessary to use a password management server and collectively manage the access rights of all persons who wish to buy the image data on the server, although no hardware is required. In the case where the scramble distribution method is employed, both software and hardware load is required, although there is no need of managing the access rights.
Since the scrambling process in the transmitter side is performed independent of a compressing process, the following drawback occurs: if the scrambling process is performed after the compressing process, it is necessary to transmit data without an error in descrambling. On the other hand, if the compressing process is performed after the scrambling process, the compression is reduced due to the reduction of a correlation between adjacent pixels.